High Voltage Capacitor Test; Door Sensing Switch; Primary Interlock Relay - Sharp R-310AK Supplemental Service Manual

R-310AK
R-330AK
R-330AW
PROCEDURE
LETTER
D

HIGH VOLTAGE CAPACITOR TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS
OR WIRING.
If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and
check for short or open between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity
for a short time and should indicate an open circuit once the capacitor is charged. If the above is not the
case, check the capacitor with an ohmmeter to see if it is shorted between either of the terminals and case.
If it is shorted, replace the capacitor.
E OVEN THERMAL CUT-OUT
A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 257˚F(125˚C).
An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and check
inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for
restricted air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
MAGNETRON THERMAL CUT-OUT
A continuity check across the thermal cut-out terminals should indicate a closed circuit. If the temperature
of the magnetron reaches approximately 203˚F(95˚C), the thermal cut-out opens. The thermal cut-out
resets automatically below approximately 167˚F (75˚C). An open thermal cut-out indicates overheating
of the magnetron. Check for restricted air flow to the magnetron, especially the cooling fan air guide.
CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,
F SECONDARY INTERLOCK SWITCH AND DOOR SWITCH TEST
Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal
of the switch. The meter should indicated an open circuit with the door open and a closed circuit with the
door closed. If improper operation is indicated, replace the secondary interlock switch.
PRIMARY INTERLOCK SYSTEM TEST

DOOR SENSING SWITCH

Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal
of the switch. The meter should indicated an open circuit with the door open and a closed circuit with the
door closed. If improper operation is indicated, replace the door sensing switch.
NOTE: If the door sensing switch contacts fail in the open position and the door is closed, the cooling

PRIMARY INTERLOCK RELAY

Disconnect two (2) wire leads from the male tab terminals of the Primary Interlock Relay. Check the state
of the relay contacts using a ohmmeter. The relay contacts should be open. If the relay contacts are
closed, replace the circuit board entirely or the relay itself.
G MONITOR SWITCH
Disconnect the oven from power supply. Before performing this test, make sure that the secondary
interlock switch and the primary interlock relay are operating properly, according to the above Switch
Test Procedure. Disconnect the wire lead from the monitor switch (NC) terminal. Check the monitor
switch operation by using the ohmmeter as follows. When the door is open, the meter should indicate
a closed circuit. When the monitor switch actuator is pushed by a screw driver through the lower latch
hole on the front plate of the oven cavity with the door
opened (in this condition the plunger of the monitor
switch is pushed in), the meter should indicate an
open circuit. If improper operation is indicated, the
switch may be defective. After testing the monitor
switch, reconnect the wire lead to the monitor switch
(NC) terminal and check the continuity of the monitor
circuit.
TEST PROCEDURES
REPLACE THERMAL CUT-OUT.
fan, turntable and oven light will be activated by RY1.
COMPONENT TEST
SCREW DRIVER
12
RED
GRY
MONITOR SWITCH
OHMMETER